For six weeks the mother of the late president, Lech Kaczynski, lay critically ill in a Warsaw hospital with no idea that her son died in a plane crash in Russia.

But the late president's twin brother, Jaroslaw Kaczynski, finally broke the news to her yesterday, a blow that came as a huge shock, according to Elzbieta Jakubiak, an aide.

In an interview for TVN24 she said: "I really feel for him today. And yet at the same time, I also think this is a relief for him."

Jaroslaw Kaczynski did not speak publicly himself about the matter, and Jakubiak said she did not have many more details because the family was spending time together in private.

Though Jaroslaw, 60, is now running for the presidency in his brother's place, he remains in mourning and has made only rare public appearances since declaring his candidacy in late April. Voting is to take place 20 June.

The news was reported in Polish papers today, which is Mother's Day in Poland. The daily Fakt tabloid said that until getting the news, the mother "was possibly the only person in Poland not to know about the tragic death of the president".

Jadwiga Kaczynska has been critically ill for many weeks and just after Kaczynski was killed in the plane crash, doctors advised the family to spare her the news until she was better. She has been hospitalised with lung and heart problems. Lech Kaczynski, in the weeks before his death, cancelled foreign trips to be by her side.

Kaczynski died on 10 April with his wife and 94 others, including some of the country's highest civilian and military leaders. It was the worst tragedy to strike Poland since the second world war.